The primary objective of this research is to develop an implantable recording electrode that will permit electrophysiological study of uncut, single taste fibers for long time periods in unanesthetized animals. An implantable electrode, that consists of a silicon chip with a sieve-like array of small holes and associated electrodes, will be placed in small tubes. The electrode and tube will then be surgically implanted in the neck of rats, with the cut glossopharyngeal nerve positioned in each end of the tube. Regenerated fibers grow through the holes in the silicon chip in apposition to electrodes. Subsequently, recordings will be made from single taste fibers in chronic preparations. Thus, techniques will be available to approach a fundamental question about the cell biology of the taste system: to what extent is the response from a single afferent fiber stable during the ongoing processes of taste bud cell turnover and synaptic remodeling? In addition we propose to use this implantable device to examine and analyze the response patterns across fibers to chemical stimulation of the tongue. These studies will contribute basic information about the stability of the single afferent response during processes of taste cell turnover and synaptic changes. This information will provide important new data about the cell biology of the taste system that can be applied to questions of neural coding in taste. In addition, development of the implantable electrode can have important applications in technology to restore function in regenerating peripheral nerves.